XYplorer is a tabbed file manager for Windows. It features a powerful file search, a versatile preview, a highly customizable interface, optional dual pane, and a large array of unique ways to efficiently automate frequently recurring tasks.
It’s fast and light, it’s innovative, and it’s portable.

To make it "portable", simply copy the XYexplorer folder from your Program Files to the USB stick.

This is one of the better give aways - a useful utility with lots of configurability. I've installed it on Windoze 7 both 64 and 32 bit machines - if you got an error I'd do as Ned suggested and download it again.